Study On Rain-Wind Induced Vibrations Of Stay Cables And Countermeasures

The stay cables are main stressed ones of structure of cable-stayed bridges. Stay cables are prone to suffer from various of vibrations, which are especially harmful to the bridge, due to their small rigidity, small mass and low damping. With the increase of the span length of cable-stayed bridges, stay cables become longer and longer, and the problems of stay cables vibrations have arose great concern in recent years. In these cases, rain-wind induced vibration of stay cables has become a matter of great concern of bridge experts for its large amplitude and low wind speed for vibrating. This thesis focuses on rain-wind induced vibration of stay cables at a certain position.The rain-wind induced vibration of stay cables is a new phenomenon of wind-induced vibration, which was originally discovered in 1980's. Currently, the generation mechanisms of rain-wind induced vibration have not yet to be reached. This thesis deeply analyzes some existing generation mechanisms and illuminates the theory basis, advantages and disadvantages of some possible generation mechanisms. In the mean time, the thesis set forth rain-wind induced vibration's characteristics and external influence factors concisely.By reproducing the rain condition in a wind tunnel, the section models which are applied in wind tunnel have three kinds of stranded steel wire cable with different diameters(235mm, 260mm, 280mm)and one kind of parallel steel wire cable(139mm) that will be used by EDong Yangtze Rive Road Bridge. The effects of several main factors such as wind speed and wind angle on the characteristics of rain-wind vibration and spiraled wires countermeasure for mitigation of the vibration are then experimentally investigated in systematically. The test results may be employed as valuable references for further studies on the mechanisms of rain-wind induced cable vibrations and practical their applications for cable-stayed bridges. In addition, This thesis also propose some structural and aerodynamic countermeasures for rain-wind induced vibrations of various stay cables and compare the advantages and disadvantages of various countermeasures for rain-wind induced vibrations.